1. Field of the Invention
The present invention relates to a system for signalling conditions of a vehicle. More particularly, the invention relates to a system for signalling an emergency within a vehicle and for signalling various of its other conditions or states if it is, for example, a commercial one such as a taxicab.
In recent years operators of commercial vehicles such as taxicabs have become increasingly more common targets for robbery, assault and other violent crimes. Typically, a criminal posing as an ordinary passenger will enter the rear seat of a taxicab and then rob or otherwise threaten the driver in the front seat who, of necessity, faces away from his passengers a large portion of the time. Since the driver is in a poor position to defend himself against such an attack, it is desirable to provide him or her with a system for attracting assistance in these instances.
The driver of any type of vehicle also may have a medical emergency that requires attention. And the vehicle can break down without warning. While these occurrences are not as menacing as a criminal attack, the driver nevertheless can benefit from a simple means for attracting attention to his or her vehicle and thereby obtaining assistance in such cases.
In addition, it is desirable that commercial vehicles such as taxicabs have a convenient mechanism for clearly signalling their commercial condition at any time. For example, most taxicabs may be "available for hire", "off-duty", or "on radio call", and is it desirable for the driver to be able to unambigously signal these conditions to those outside of his or her cab. It is also desirable to arrange signals having contractory meanings, such as "available for hire" and "off-duty" so that they cannot be operated simultaneously.
2. Description of the Prior Art
Various signalling devices for vehicles, including devices for signalling an emergency within a vehicle, have been proposed in the past. For example, U.S. Pat. No. 1,857,210 (Nelson et al.) relates to an automobile signaling device that includes a housing divided into two compartments, each of which encloses a light bulb. These bulbs may selectably be actuated to signal either left or right turns on the vehicle. A warning light, mounted on the roof of the housing and enclosed by a colored glass dome, may be lit to attract attention to the vehicle. However, the warning light is projected in all directions in a plane above the roof of the housing.
U.S. Pat. No. 2,891,140 (Huff) relates to a vehicular warning light that is recessed in the roof of a vehicle and faces rearwardly. The light is actuated by a switch mounted to be readily accessible to occupants of the vehicle.
U.S. Pat. No. 3,947,815 (Muncheryan) relates to an automobile emergency-alerting system similar to that shown in the Huff Patent, and includes a siren and a rearwardly facing warning light mounted on the trunk lid of an automobile. The light and siren are operable simultaneously through any one of a number of switches mounted inside the automobile.
Each of the vehicular emergency warning systems described in the patents mentioned above is characterized by certain drawbacks. More particularly, the systems of the Huff and Muncheryan Patents are visible generally only from the rear of the vehicle. Therefore, they are not well suited to attract attention of passersby in front of the vehicle. It is also believed that a criminal is likely to become agitated and hurried and, therefore, more likely to attack the driver if he is aware that the driver is attempting to signal for assistance. Therefore, it is believed that systems such as that shown in the Nelson Patent in which a warning light is projected in all directions laterally of the vehicle and can be readily reflected back to the interior vehicle, and that shown in the Muncheryan Patent in which a siren sounds when a warning light is operated, are not advantageous.
Still other vehicular distress or condition signalling systems are shown in U.S. Pat. Nos. 3,493,924 (Dobbins); 2,345,979 (Ivey et al.); 1,968,759 (Donner); 2,866,175 (Slater); and 1,346,567 (Stover).